Fabrication of Gradient Structure and Al–Ce Coating for Enhanced Corrosion Resistance of 7075 Aluminum Alloy

Corrosion remains a critical challenge to the reliable operation of 7075 aluminum alloy components in offshore oil platform hinge systems. This study proposed a novel ultrasonic strengthening grinding process (USGP) incorporating Al-Ce mixed microscale particles to enhance the corrosion resistance of 7075 aluminum alloy. An Al-Ce composite layer comprising a functional coating and gradient structure was formed, characterized by a fine-grained microstructure with high-density low-angle grain boundaries (LAGBs). Electrochemical measurements revealed that the USGP-treated sample exhibited a corrosion current density and corrosion rate of approximately 1.54 × 10^-4 A/cm² and 1.613 mm/year, respectively, corresponding to reductions of about 60.41% compared to the untreated sample. This improvement is primarily attributed to the Al₂O₃ coating, which effectively inhibits direct contact between corrosive media and the substrate, while the CeO₂ coating released ions that reacted with corrosion products to form protective precipitates. Finally, a predictive model was established to evaluate the synergistic contributions of microstructural characteristics and electrochemical parameters to corrosion resistance. This study provides a promising strategy for enhancing the corrosion resistance of 7075 aluminum alloy components used in offshore platform hinge systems.